Class 1's 2.1A foam system is a flow based foam concentrate proportioning system that uses a field-proven flow sensor assembly to measure actual water flow from the fire pump discharge. The digital input of the flow sensor and the actual output of the positive displacement piston foam concentrate pump are constantly compared and updated by the controller which automatically adjusts the desired foam concentrate rate injected into the discharge. It has full function digital control with push button operation for ease of use. The digital foam system removes the traditional pressure restrictions of other foam systems so it is unaffected by hose length, flow rate, or pressures.